Linac Laser Notcher Status David Johnson Todd Johnson, Vic Scarpine, Andrea Saewert, John Sobolewski PIP Meeting March 6, 2013 Beams Doc 4306

Laser Notcher System Major Components of the system – Optical pulse generation – Fiber amplifier system (2 + 1 stages) – Macro pulse generation (at 15 Hz) (Pockels cell) – Free space laser amplifier – Laser transport and beam shaping / optical cavity – Vacuum chamber and integration into MEBT Prototype using 3D printer in TD – Timing and controls DEJ PIP Status Report Beams Doc 4306

Burst mode seed pulses to Fiber Amplifier followed by Free Space Amp 1 =1064nm 120 mW CW SW=0.1 nm 10 GHz Mach-Zehnder Modulator Pulse Generator Amplifier, Timing PM Fiber L ins ~5dB L i ~1.8dB 15 Hz Pockels cell Updated 10/3/2012 Generate 24 us burst at 15 hz TRANSPORT BEAM SHAPING OPTICS & OPTICAL CAVITY Fiber Pre-Amp Fiber Amp 1 Fiber Amp 2 Free Space Amp Output modulator/Input fiber pre-amp: MHz pulses (1.25 ns pulse), 458kHz burst Clean up filter Isolator Line filter Free Space Grumman CEO DPSS OEM Diode + TC controlled *Notch 12 bunches -> 60 ns 10 notches/linac pulse Measurement point DEJ PIP Status Report Beams Doc 4306

Status of the OPG and Fiber Amp We set up the optical pulse generation/fiber amplifier system in the new A0 instrumentation laser laboratory. We now have the seed laser and fiber amplifiers connected to the safety interlock system and have procedures in place and permission to operate the equipment on hand. We have started characterizing the characteristics of the system using a borrowed pulse generator and scope/spectrum analyzer in the A0 lab. DEJ PIP Status Report Beams Doc 4306

OPG Fiber Amp Components Diode/TEC power supply Safety System interface Modulator Bias Controller Fiber Pre-amp Fiber Amp 1 P.S. for RF Amp DEJ PIP Status Report Beams Doc 4306

Optical components Seed Source RF Amp FBG / isolator & fiber holder Modulator Narrow band Optical filter Photodiode detector All this to be mounted inside a chassis DEJ PIP Status Report Beams Doc 4306

Current support equipment Borrowed from Peter Preito – HP 8131A 500 MHz pulse generator – RF splitter Instrumentation (Carl Lundberg) – Power supply for RF amplifier Equipment in A0 Instrumentation laser lab (Vic Scarpine/Andrea Saewert) – Tektronix TDS GHz/10 GS/s oscilloscope – Agilent 86142B Optical Spectrum Analyzer – Thorlab’s fiber coupled photodiode DET01CFC – Miscellaneous lab supplies… DEJ PIP Status Report Beams Doc 4306

200 MHz Laser Pulses 200 MHz pulsed from: HP pulse generator input into modulator RF amplifier 200 MHz Laser pulses (1.25 ns flattop) out of fiber pre-amp with (band pass filter included) * I didn’t have a blank floppy disk with me 200 MHz pulses 450 kHz I need to add another pulser to trigger the HP at 450 kHz to create the burst structure DEJ PIP Status Report Beams Doc 4306

Picosecond Pulse Labs Model PSPL Screen Shots Burst rep rate of 450kHz Seven 200MHz pulses Decreasing time/division 1.5ns FWHM pulse width DEJ PIP Status Report Beams Doc 4306

Seed Source Seed source 50 mW with 1.6 dB isolator -> mW Measured 34.8 mW with Thorlabs PM20CH (15.4 dBm) Factory Calibration 11.4 dBm User calibration Installed user calibration based upon power meter. This gives a closer result dBm (33.5 mW) - <4% dBm Line broadening of seed? Measured power in seed source with OSA Found: 11.4 dBm (13.8 mW) ---way too low ??? DEJ PIP Status Report Beams Doc 4306

Modulator and Preamp DC extinction ~ 25 dB Pump 600 mA Seed on/off Spectrum from pre-amp thru the Band Pass filter Span 100 nm Span 5 nm 22.8 dBm ~190 mW (~ nJ pulse energy) Note: operating seed at half power Modulator DEJ PIP Status Report Beams Doc 4306

Vacuum chamber The vacuum flange and beam pipe containing view ports and zig-zag cavity will prototyped using the 3D printer in TD. – Make new RFQ flange (thicker) with view port and internal optical cavity supports. Must fit in this space DEJ PIP Status Report Beams Doc 4306

Summary We have assembled and starting to characterize the first components for the Laser Notcher. Will continue to learn how to operate the OPG and fiber amplifiers. We would like to put the OPG equipment inside a chassis to protect fibers and get rid of external power supply for RF amplifier. We will add another pulse generator to create 450 kHz burst. The temporal pulse structure out of the borrowed pulse generator is not as uniform as needed, but will work till we get the final pulser. We have not spent much time on the beam shaping optics since we demonstrated beam shaping and zig-zag cavity last fall. We need to add in an anamorphic prism pair to better shape the horizontal beam out of the piShaper to move forward with the design. Todd has been working on the free space amplifiers at NML which are very similar to those we will be using next year for the final amplification stage. John Sobolewski (MS co-op) is beginning to look at the vacuum holder for the optical cavity. We are planning to prototype this using the 3D printer. This summer add in the Pockels cell to create 15 Hz burst of pulses. By end of FY13 we should be ready to add new pulse generator, final fiber amplifier, and free space amplifier. DEJ PIP Status Report Beams Doc 4306